The present invention relates to devices for cleaning dialyzer headers.
Hemodialysis is an extracorporeal therapy whereby blood is pumped out of the body and through a dialyzer, also know as an artificial kidney, and returned back to the body. The dialyzer is composed of two regions: a blood region and a dialysate region, the two regions being separated from one another by a filter-like membrane possibly composed of hollow fibers or flat sheets. The membrane is porous and permits water and small and middle weight molecules to pass across.
The blood that is pumped out of the body is pumped through the blood region of the dialyzer. Dialysate, a fluid that contains the electrolytes the body needs and bicarbonate to aid in acid base balance in the body, is caused to flow through the dialysate region in counter current to the blood flow through the blood region. Toxins in the blood pass across the membrane from the blood region into the dialysate region by diffusion or convection. Electrolytes and bicarbonate pass from the dialysate in the dialysate region across the membrane into the blood region in a similar manner.
Many dialysis facilities reuse the dialyzers in order to save money. The costs associated with dialyzer reuse include: reuse space, water and electricity, the cost of machines specifically designed to reprocess the dialyzers, reprocessing chemicals, and employee salaries.
The steps involved in dialyzer reuse vary from clinic to clinic. However, certain steps are universal. After completion of a dialysis treatment, the first step in the reuse process is to rinse any residual blood out of the dialyzer. For this purpose, the dialyzer is connected to a water supply and fluid is flushed through the blood and/or dialysate regions. This process rinses out many of the large particles and blood components left in the dialyzer. After the dialyzer is rinsed the dialyzer is then reprocessed.
Although many clinics throughout the world manually reprocess the dialyzers, there are currently many machines, such as those marketed by Alcavis International, Inc. under the trade name ARM, Minntech Corp. under the trade name Renatron, Mesa Medical under the trade name Echo, etc., that are capable of automatically reprocessing dialyzers.
Automatic reprocessing is similar to manual reprocessing. In automatic reprocessing, the dialyzer is connected to the reprocessing machine by both blood ports (arterial and venous) and both dialysate ports. Water or other cleaning liquid is then flushed through both regions of the dialyzer to further rinse away blood products. This is done in several steps. The cleaning step of dialyzer reprocessing is performed by flushing a cleaning solution through the dialyzer. This is also performed in other steps including a backflush. The backflush process rinses the water and cleaning agent from the dialysate side through the membrane to the blood region and out of the blood region ports. This backflush process can loosen and remove any blood or blood products that are adhered to the inner wall of the dialyzer fibers.
Most reused dialyzers are taken out of use, or fail, because the volume of the dialyzer, i.e., the volume of the blood compartment, has dropped below acceptable levels. Any blood products that block the fibers will reduce the volume of the dialyzer. Very rarely does a dialyzer fail due to inadequate results on a leak test.
The headers of a dialyzer are the parts of the dialyzer where the blood enters and leaves the dialyzer. During dialysis, as blood is pumped through the dialyzer, microclots, fibrin and other biologic products react with the dialyzer and may also react with the extracorporeal circuit consisting of blood lines, the pump and the dialysate compartment. These biologic products commonly accumulate in the headers of the dialyzer, many times forming a sheet that can completely block the openings to the fibers and blood region of the dialyzer.
These biologic products must be removed from the dialyzer in order to obtain adequate blood volume during reuse testing. Currently, flushing water is the most common method used to remove the biologic products from the header of the dialyzer. However, due to the design of the dialyzer header, this is not always effective. Some dialyzers have header caps that can be unscrewed to facilitate cleaning. However, due to concerns of cross contamination, the complexity of properly reassembling such a dialyzer and damage to the dialyzers, removing the header caps is discouraged.
U.S. Pat. Nos. 6,050,278 by Arnal et al and 4,375,413 by Geel et al disclose dialyzer cleaning devices having needles for injecting water into the dialyzer head. The device disclosed by Geel et al has a single solid piece for spraying water, which is not capable of rotating or retracting. Arnal et al disclose a needle that may oscillate and retract. Oscillation is effected by a gear assembly that undergoes reciprocal motion created by a pulsating fluid. Thus, this is a structurally complex device.